Victoria, Christopher, Claire and Roshel share the same hobby of collecting stamps. The average number of stamps collected by the 4 friends is 29. Christopher collected 7 more stamps than Claire but 18 fewer stamps than Victoria. Roshel collected 4 stamps fewer than Claire. Find the average number of stamps collected by Christopher and Roshel. Round off your answer to the nearest whole number.
Number of stamps Claire collected = 1 u
Number of stamps Christopher collected = 1 u + 7
Number of stamps Victoria collected = 1 u + 7 + 18 = 1 u + 25
Number of stamps Roshel collected = 1 u - 4

Total number of stamps collected
= 4 x 29
= 116

Total number of stamps collected in units
= 1 u + 1 u + 7 + 1 u + 25 + 1 u - 4
= 4 u + 28

4 u + 28 = 116
4 u = 116 - 28 = 88

1 u = 88 ÷ 4 = 22

Total number of stamps collected by Christopher and Roshel
= 1 u + 7 + 1 u - 4
= 2 u + 3
= 2 x 22 + 3
= 47

Average number of stamps collected by Christopher and Roshel
= 47 ÷ 2
≈ 24 (Round off to the nearest whole number.)

Answer(s): 24